A two-dimensional capacitive touch panel includes a plurality of X-traces and a plurality of Y-traces mutually intersected to form a plurality of sensors. When an electrically conductive article such as a finger approaches a sensor, the coupling capacitor between the finger and the sensor will increase the capacitance on the trace connected to the sensor, so a detector circuit can locate the finger on the capacitive touch panel by detecting the capacitance variations of the traces, and then convert the position coordinates into information for a host to perform corresponding operation.
In further detail, as shown in FIG. 1, when a finger touches the intersection point between a Y-trace Y1 and X-traces X4 and X5, the measured capacitances from those X-traces X1, X2, X7 and X8 that are far from the finger will not be affected by the finger and remain below a threshold CTH, the measured capacitances from those X-traces X3 and X6 near the finger will be increased to slightly higher than the threshold CTH, the measured capacitance from the X-trace X5 is even higher, and the measured capacitance from the X-trace X4 where the finger touches is at the peak of the curve 10 established by the measured capacitances from the X-traces X1-X8. Similarly, the measured capacitance from the Y-trace Y1 is at the peak of the curve established by the measured capacitances from the Y-traces, since the Y-trace Y1 is touched by the finger. Therefore, the capacitive touch panel can identify the touch point (X4,Y1). The capacitances on the X-traces X1, X2, X7 and X8 are not affected by the finger, so the measured capacitances therefrom are too low to be useful in the subsequent conversion and calculation for identification of the touch point.
To acquire a frame of information, a capacitive touch panel always scans all of its traces sequentially and combines the measured capacitances from the traces to construct a frame for locating a touch point on the capacitive touch panel. The present invention provides a novel detect method of a capacitive touch panel to reduce operation of the detector circuit of a capacitive touch panel to improve performance of the capacitive touch panel.